The advancement of late Badenian (Middle Miocene) transgression in the Carpathian Foreland recorded by foraminiferal assemblages: Kudryntsi on Zbruch River (Ukraine)

Abstract

The upper Badenian section of the Kudryntsi quarry (Ukrainian Carpathian Foreland Basin) consists of the Ternopil and Prut members of the Kosiv Formation. Its lower part was previously described by Gedl and Peryt (2011), and here we report a 5.3 m thick newly-exposed upper part of the section. Fifty-five species of benthic foraminifera and five species of planktonic foraminifera occur there. Benthic foraminifera are represented by both calcareous and agglutinated forms. Planktonic foraminifera occur in the whole of the succession studied. Five benthic foraminiferal assemblages are recognized: Assemblage VIII (Elphidium–Lobatula), Assemblage IX (Cibicidoides), Assemblage X (Uvigerina–Bulimina), Assemblage XI (Heterolepa) and Assemblage XII (Uvigerina–Bulimina–agglutinated). The foraminiferal record indicates deposition in a shallow subtidal environment of normal marine salinity and temperate waters followed by gradual deepening of the basin to >50 m. Analysis of foraminiferal assemblages indicates that bottom waters were highly oxygenated during deposition of the lower and middle parts of the interval studied. During deposition of the upper part of the sequence, the oxygenation of bottom water decreased, as indicated by a large decrease in the proportion of oxic species and an increase in dysoxic taxa.